1. Field of the Invention
The present invention relates to an ultrasonic motor unit including an ultrasonic motor using a transducer such as a piezoelectric element.
2. Description of the Related Art
Recently, attention has been paid to an ultrasonic motor using the vibration of a transducer such as a piezoelectric element as a new motor replacing an electromagnetic type motor. This ultrasonic motor is superior to a conventional electromagnetic type motor in being capable of obtaining low-speed high thrust without gears, having high holding force, having high resolution, being low noise, producing no magnetic noise, and the like.
More specifically, there is known an ultrasonic motor of a type that excites elliptic vibration by applying a predetermined alternating voltage to the transducer and frictionally drives a driven member by using the elliptic vibration as a driving source. As a technique associated with such an ultrasonic motor, for example, the following technique is disclosed in Jpn. Pat. Appln. KOKAI Publication No. 11-235062.
That is, the vibration actuator driving device disclosed in Jpn. Pat. Appln. KOKAI Publication No. 11-235062 includes a transducer which vibrates in accordance with a driving signal, a ring-like relative motion member which is in contact with the transducer and makes relative motion in accordance with the vibration of the transducer, and a pressurizing support member which brings the transducer into contact with the relative motion member with pressure while supporting the transducer. In this case, the pressurizing support member includes a ring-like base portion, a leaf spring portion cantilevered to the base portion, and a support pin portion provided on the free end portion side of the leaf spring portion. According to the technique disclosed in Jpn. Pat. Appln. KOKAI Publication No. 11-235062, a vibration actuator driving device which can be mounted in even a small mounting space is provided.
The technique disclosed in Jpn. Pat. Appln. KOKAI Publication No. 11-235062 can drive a driven member only within a predetermined plane. For this reason, in order to implement an arrangement which can drive a driven member not only in an x-y plane but also in the z-axis direction perpendicular to the x-y plane, it is necessary to add a driving mechanism corresponding to another axis. In order to operate these driving mechanisms in cooperation with each other, some technical contrivance is required for the pressurizing support member as a pressing mechanism in terms of arrangement. Obviously, adding a driving mechanism corresponding to one axis will increase the size of the device itself. That is, increasing the degree of freedom of driving directions will increase the size of the device.